GW Hesitates and misses under load at low RPM

[lanierboy]

I have an '87 GW with a Projection 2bbl system on it. It runs smooth at all RPM's while the transmission is in neutral but, It will stumble (I assume missing) at low RPM's under load. It runs smooth at high rpm's under load.

Any ideas?

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1987 GW "Christine"
AMC360 / NP229 / TF727
Holley Projection 2bbl
TFI Ignition upgrade
Skyjacker 4" Spring lift
GoodYear Workhorse 31/10.5
My Web (http://members.home.net/lanierboy/)

[SpruceMoose]

sounds like mine just after i installed it. i spent a lot of time tweeking the mixture at different rpms in neutral. when i went to drive it it died. i had to raise the fuel pressure a little bit, and then it worked fine. but, since it runs ok at high rpms, maybe just the idle and mid-range pots need adjusting. btw, got a mixture gage or the closed-loop system on it?

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88 Grand Wagoneer
"Spruce Moose"
http://www.FSJtheMoose.homestead.com/files/small_jeep_in_woods_1_cropped.gif
AMC 360, DANA 44 F/R 2.72, TF 727, NP 229
Jacobs Pro-Street Ignition, Edelbrock 4bbl Intake with Holley 2bbl Analog Pro-Jection
Flowmaster 2.5" 50 Series Delta muffler and tubing
Amzoil foam air filter, Amzoil fluids all around
30x9.5 BFG AT
HF,VHF,UHF ham rigs and too many antennas (not)
8-Ball shift knob from college (1975)
Hella aux. driving lights

Next: 3" Rough Country 4-spring lift, Killer32 Bumpers and nerfs, 31 or 32" A/Ts

Mileage? We don't need no stinkin' mileage!

[lanierboy]

I have the O2 sensor to close the loop. I assume it's working correctly.

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1987 GW "Christine"
AMC360 / NP229 / TF727
Holley Projection 2bbl
TFI Ignition upgrade
Skyjacker 4" Spring lift
GoodYear Workhorse 31/10.5
My Web (http://members.home.net/lanierboy/)

[SpruceMoose]

OK. now, i know the older, analog system (like mine) has a seperate closed-loop box with a red mixture LED on it. i dont know about the digital systems. If yours has a mixture light you can see if the mixture is too lean (light out) or too rich (light on). its a wonderful diagnostic tool! except when it isnt working all the time, like mine. right now it shows red all the time.

another thing to check is the plugs. if gapped too wide they can "blow out" under load.

sm